diff --git a/backend/src/modules/chat/chat.module.ts b/backend/src/modules/chat/chat.module.ts
index 88ee0b2..e21bc66 100644
--- a/backend/src/modules/chat/chat.module.ts
+++ b/backend/src/modules/chat/chat.module.ts
@@ -30,6 +30,6 @@ import { User, UserSchema } from '../user/user.schema';
     { provide: 'IChatRepository', useExisting: ChatRepositoryMongodb },
     { provide: 'IMessageRepository', useExisting: MessageRepositoryMongodb },
   ],
-  exports: [ChatService],
+  exports: [ChatService, 'IChatRepository'],
 })
 export class ChatModule {}
\ No newline at end of file
diff --git a/backend/src/modules/chat/domain/chat.repository.ts b/backend/src/modules/chat/domain/chat.repository.ts
index b1113ed..fed5979 100644
--- a/backend/src/modules/chat/domain/chat.repository.ts
+++ b/backend/src/modules/chat/domain/chat.repository.ts
@@ -1,20 +1,63 @@
-import { ChatDetails, ChatStatus } from './chat.entity';
+/* eslint-disable @typescript-eslint/unbound-method */
+import { randomUUID } from 'crypto';
+import { ITicketRepository } from '../../../domain/repository/ticket.repository.interface';
+import { Ticket, TicketStatus } from '../../../domain/entities/ticket.entity';
+import { NewAgentTicketUseCase } from './newAgent.usecase';
+import { ChatService } from '../../../../chat/application/chat.service';
 
-export interface IChatRepository {
-  create(data: {
-    ticketId: string;
-    clientId: string;
-    agentId: string;
-    groupId: string;
-  }): Promise<ChatDetails>;
+describe('NewAgentTicketUseCase', () => {
+  let repository: jest.Mocked<ITicketRepository>;
+  let chatService: jest.Mocked<ChatService>;
+  let useCase: NewAgentTicketUseCase;
+  let ticket: Ticket;
 
-  findById(id: string): Promise<ChatDetails | null>;
+  beforeEach(() => {
+    ticket = Ticket.create({
+      title: 'titulo do ticket',
+      category: 'bi',
+      description: 'descricao do ticket',
+      clientId: randomUUID(),
+    });
 
-  findByParticipant(userId: string): Promise<ChatDetails[]>;
+    repository = {
+      readById: jest.fn(),
+      save: jest.fn(),
+    } as unknown as jest.Mocked<ITicketRepository>;
 
-  findByTicketId(ticketId: string): Promise<ChatDetails | null>;
+    // Usando o mock do ChatService conforme o padrão da develop
+    chatService = {
+      updateAgentByTicketId: jest.fn(),
+    } as unknown as jest.Mocked<ChatService>;
 
-  updateStatus(id: string, status: ChatStatus): Promise<ChatDetails | null>;
+    useCase = new NewAgentTicketUseCase(repository, chatService);
+  });
 
-  updateAgent(ticketId: string, agentId: string | null): Promise<ChatDetails | null>;
-}
+  it('should assign a new agent to a ticket successfully and update the chat', async () => {
+    const input = {
+      id: ticket.id,
+      agentId: randomUUID(),
+    };
+
+    repository.readById.mockResolvedValue(ticket);
+    ticket.assignToAgent(input.agentId);
+    repository.save.mockResolvedValue(ticket);
+
+    const output = await useCase.execute(input);
+
+    expect(output).toBeDefined();
+    expect(output.id).toBe(ticket.id);
+    expect(output.agentId).toBe(input.agentId);
+    expect(output.status).toBe(TicketStatus.IN_PROGRESS);
+
+    expect(repository.readById).toHaveBeenCalledTimes(1);
+    expect(repository.readById).toHaveBeenCalledWith(input.id);
+    expect(repository.save).toHaveBeenCalledTimes(1);
+
+    expect(chatService.updateAgentByTicketId).toHaveBeenCalledTimes(1);
+    expect(chatService.updateAgentByTicketId).toHaveBeenCalledWith(ticket.id, input.agentId);
+
+    expect(output).not.toHaveProperty('toPrimitives');
+    expect(output).not.toHaveProperty('escalate');
+    expect(output).not.toHaveProperty('assignToAgent');
+  });
+});
\ No newline at end of file
diff --git a/backend/src/modules/chat/infra/chat.repository.mongodb.ts b/backend/src/modules/chat/infra/chat.repository.mongodb.ts
index d980d36..3e12625 100644
--- a/backend/src/modules/chat/infra/chat.repository.mongodb.ts
+++ b/backend/src/modules/chat/infra/chat.repository.mongodb.ts
@@ -39,7 +39,7 @@ export class ChatRepositoryMongodb implements IChatRepository {
 
   async findById(id: string): Promise<ChatDetails | null> {
     const chatDoc = await this.chatModel.findById(id).exec();
-         
+          
     if (!chatDoc) return null;
     return {
       id: chatDoc._id as string,
@@ -53,7 +53,7 @@ export class ChatRepositoryMongodb implements IChatRepository {
 
   async findByTicketId(ticketId: string): Promise<ChatDetails | null> {
     const chatDoc = await this.chatModel.findOne({ ticketId }).exec();
-         
+          
     if (!chatDoc) return null;
     return {
       id: chatDoc._id as string,
@@ -93,4 +93,4 @@ export class ChatRepositoryMongodb implements IChatRepository {
     if (!doc) return null;
     return this.toDetails(doc);
   }
-}
+}
\ No newline at end of file
diff --git a/backend/src/modules/ticket/application/useCases/newAgent/newAgent.usecase.spec.ts b/backend/src/modules/ticket/application/useCases/newAgent/newAgent.usecase.spec.ts
index ff346f5..d6eb2cf 100644
--- a/backend/src/modules/ticket/application/useCases/newAgent/newAgent.usecase.spec.ts
+++ b/backend/src/modules/ticket/application/useCases/newAgent/newAgent.usecase.spec.ts
@@ -1,10 +1,7 @@
 /* eslint-disable @typescript-eslint/unbound-method */
 import { randomUUID } from 'crypto';
 import { ITicketRepository } from '../../../domain/repository/ticket.repository.interface';
-import {
-  Ticket,
-  TicketStatus,
-} from '../../../domain/entities/ticket.entity';
+import { Ticket, TicketStatus } from '../../../domain/entities/ticket.entity';
 import { NewAgentTicketUseCase } from './newAgent.usecase';
 import { ChatService } from '../../../../chat/application/chat.service';
 
@@ -34,14 +31,13 @@ describe('NewAgentTicketUseCase', () => {
     useCase = new NewAgentTicketUseCase(repository, chatService);
   });
 
-  it('should assing a new agent to a ticket successfully', async () => {
+  it('should assign a new agent to a ticket successfully', async () => {
     const input = {
       id: ticket.id,
       agentId: randomUUID(),
     };
 
     repository.readById.mockResolvedValue(ticket);
-
     ticket.assignToAgent(input.agentId);
     repository.save.mockResolvedValue(ticket);
 
@@ -54,12 +50,13 @@ describe('NewAgentTicketUseCase', () => {
 
     expect(repository.readById).toHaveBeenCalledTimes(1);
     expect(repository.readById).toHaveBeenCalledWith(input.id);
-
     expect(repository.save).toHaveBeenCalledTimes(1);
     expect(repository.save).toHaveBeenCalledWith(ticket);
+    expect(chatService.updateAgentByTicketId).toHaveBeenCalledTimes(1);
+    expect(chatService.updateAgentByTicketId).toHaveBeenCalledWith(ticket.id, input.agentId);
 
     expect(output).not.toHaveProperty('toPrimitives');
     expect(output).not.toHaveProperty('escalate');
     expect(output).not.toHaveProperty('assignToAgent');
   });
-});
+});
\ No newline at end of file
diff --git a/backend/src/modules/ticket/application/useCases/newAgent/newAgent.usecase.ts b/backend/src/modules/ticket/application/useCases/newAgent/newAgent.usecase.ts
index 8f80b46..e5380a6 100644
--- a/backend/src/modules/ticket/application/useCases/newAgent/newAgent.usecase.ts
+++ b/backend/src/modules/ticket/application/useCases/newAgent/newAgent.usecase.ts
@@ -27,7 +27,7 @@ export class NewAgentTicketUseCase {
     if (!foundedTicket) {
       throw new Error('Ticket not found.');
     }
-
+    
     foundedTicket.assignToAgent(input.agentId);
 
     const updatedTicket = await this.repository.save(foundedTicket);
@@ -39,7 +39,6 @@ export class NewAgentTicketUseCase {
     try {
       await this.chatService.updateAgentByTicketId(updatedTicket.id, updatedTicket.agentId);
     } catch (e) {
-      // Ignora se o chat não existir, pois os módulos estão fracamente acoplados
       console.warn('Chat não pôde ser atualizado ou não existe:', e);
     }
 
@@ -49,4 +48,4 @@ export class NewAgentTicketUseCase {
       status: updatedTicket.status,
     };
   }
-}
+}
\ No newline at end of file